1. Field of the Invention
This invention relates to dye complexing polymers, and, more particularly, to water soluble poly(isopropenylpyridine) betaines containing a quaternary nitrogen and a carboxylate salt or carboxylic acid group. The polymers herein have effective dye complexing properties for use, for example, laundry detergent and fabric softener compositions.
2. Description of the Prior Art
Dye complexing polymers have been used in laundry detergent and fabric softener compositions. In such application, during washing a mixture of colored and white fabrics, some of the dyes may bleed out of a colored fabric under washing conditions. The degree of bleeding is influenced by the structure of the dye, the type of cloth and the pH, temperature and mechanical efficiency of the agitation process. The bled dye in the wash liquor can be totally innocuous and get washed off in the wash liquor. However, in reality, this fugitive dye has a tendency to redeposit, either onto the same fabric or onto another fabric leading to patches and an ugly appearance of the washed material. This redeposition of the bled dye can be inhibited in several ways. One method is to introduce compounds which can complex with the fugitive dye and get washed off thus preventing redeposition.
Polyvinylpyrrolidone (PVP), by virtue of its dye complexation ability, has been used to inhibit dye deposition during washing of colored fabrics under laundry conditions. The performance of PVP as a DTI, however, is adversely affected by the presence of anionic surfactants in the washing process.
Other polymers which have been used as DTIs in laundry detergent compositions include polyvinylpyridine N-oxide (PVPNO); polyvinylimidazole (PVI) and copolymers of polyvinylpyridine and polyvinylimidazole (PVP-PVI).
U.S. Pat. Nos. 5,776,879; 5,929,175; 5,8619,442; 5,863,880, assigned to the same assignee as herein are related to this invention.
The other prior art in this field is represented by the following patents and publications:
Accordingly, it is an object of this invention to provide new and improved water soluble dye complexing polymers.
Another object herein is to provide water soluble dye complexing polymers which are effective in laundry detergent compositions containing an anionic surfactant.
A feature of the invention is the provision of a water soluble poly(isopropenylpyridine) betaine containing a quaternary nitrogen and a carboxylate salt or carboxylic acid group.
Another feature of the invention is the provision of laundry detergent compositions containing such new and improved water soluble polymers, which exhibit color stability during storage, and particularly effective dye complexing properties during the washing process even in the presence of anionic surfactants.
Among the other objects and features of the invention is to provide such polymers having dye complexing properties useful in fabric softener and textile dye treatment compositions.
What is described herein is a water soluble poly(isopropenylpyridine betaine) polymer which contains a quaternary nitrogen and a carboxylate salt or carboxylic acid group. The polymer has the formula: 
where m is indicative of the degree of polymerization;
X is an anion;
R1 and R2 are independently hydrogen, alkyl or aryl;
R3 and R4 are independently hydrogen or alkyl, with the proviso that at least one is alkyl;
n is 1-5;
M is a cation or H; and
S and T are each independently hydrogen or alkyl.
Preferred embodiments of the invention are polymers in which X is a halide; most preferably chloride or bromide; R1 and R2 are both hydrogen; R3 is alkyl, preferably methyl and R4 is hydrogen, n is 1; M is an alkali metal or H; preferably sodium or potassium; and the polymer is 25-100% quaternized; most preferably 75-100%; and S and T are both hydrogen.
A preferred polymer has a weight average molecular weight of about 5,000 to 1,000,000; preferably 20,000 to 200,000, where m is about 30-5000, preferably 100-1000. Water soluble copolymers of the defined polymer above with polymerizable comonomers, such as vinyl pyrrolidone, vinyl imidazole, acrylamide and vinyllcaprolactam also are useful herein.
The polymers of the invention have effective dye complexing properties for use in laundry detergent compositions which include at least 1% by weight of an anionic, cationic or non-ionic surfactant or mixtures thereof.
In accordance with the invention, there is described herein a water soluble poly(isopropenylpyridine) betaine containing a quaternary nitrogen and a carboxylate salt or carboxylic acid group. This polymer has dye complexing properties, particularly for use in laundry applications, having the formula: 
where m is indicative of the degree of polymerization;
X is an anion;
R1 and R2 are independently hydrogen, alkyl or aryl;
R3 and R4 are independently hydrogen or alkyl with the proviso that at least one is alkyl;
n is 1-5;
M is a cation or H; and
S and T are independently hydrogen or alkyl.
Preferred embodiments of the invention are polymers in which X is a halide; most preferably chloride or bromide; R1 and R2 are both hydrogen; R3 is alkyl, preferably methyl and R4 is hydrogen; n is 1; M is an alkali metal or H; preferably sodium or potassium; and the polymer is 25-100% quaternized; most preferably 75-100%; and S and T are both hydrogen.
A preferred polymer has a weight average molecular weight of about 5,000 to 1,000,000; preferably 20,000 to 200,000, where m is about 30-5000, preferably 100-1000. Water soluble copolymers of the defined polymer above with polymerizable comonomers, such as vinyl pyrrolidone, vinyl caprolactam, vinyl imidazole, N-vinyl formamide, and acrylamide also are useful herein.
A preferred use of the polymer and copolymers herein is in laundry detergent compositions which includes about. 0.01-10% of the polymer or copolymer, which will provide about 2-1000 ppm of the polymer or copolymer during laundry use.
In a preferred embodiment of the invention, the water soluble polymers of the invention are made by polymerizing a suitable isopropenylpyridine under suitable polymerization conditions to form a poly(isopropenylpyridine) intermediate, and then reacting the intermediate polymer with sodium chloroacetate in an aqueous medium. The reaction product is a poly(isopropenylpyridine) betaine polymer containing a quaternary nitrogen and a carboxylate salt or carboxylic acid group.
In the polymerization step, which may be solution, precipitation or emulsion polymerization, any suitable solventlimay be used, for example, an alcohol, such as methanol, ethanol or isopropanol; water; or mixtures of water and alcohol. The reaction temperature is about 40xc2x0 to 150xc2x0 C., preferably 50xc2x0 to 90xc2x0 C., and most preferably about 60xc2x0 to 85xc2x0 C. The polymerization initiator is a free radical initiator, such as perester, peroxide, percarbonate, or Vazo(copyright) type initiators may be used. The polymerization is carried out at a solids level of about 5 to 80%, preferably 20 to 50%.
A preferred polymer* herein is poly(4-isopropenylpyridine) sodium carboxymethyl betaine chloride having the formula: 